Device for automatically actuating a door, in particular a vertical door

ABSTRACT

The invention relates to a device for automatically actuating a door, in particular a vertical door, which aims to replace to a great extent known signal generation devices or control signal sensors for opening the door or for the security monitoring of the closing motion of the door. This is achieved by a detector of a security system, which is configured as a scanner detector and operates according to reflective principles, for monitoring an area by allocation to one of the ground level aprons of the door, said detector being mounted in the vicinity of a lateral border of the door opening, at a height, which is adjusted to the maximum height of objects supported on the relevant apron that are not to be registered as obstacles. The scanning beam of said detector scans a horizontal fan-shaped area, which covers the relevant apron and has a low vertical depth, determined by the depth of the scanning beam, as the monitoring area. The radial dimension of said fan-shaped area, which is determined by the maximum measuring range of the scanning detector, is selected according to the size of the relevant apron.

This application is the US national phase of international applicationPCT/EP03/00809 filed 27 Jan. 2004, which designated the US and claimspriority to DE Application No. 102 03 145.2 filed 28 Jan. 2002. Theentire contents of these applications are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a device for automatically activating a door,in particular a lifting door, which has an essentially vertical openingplane, an inner side and an outer side, and approach areas which arelevel with the floor and are respectively located on the inner side andon the outer side.

2. Description of Related Art

It is generally known that with automatically activated doors it isnecessary to take safety precautions to prevent obstructing objects orpersons who are located in the door opening from being damaged orinjured when the door is automatically closed.

For this purpose, it has been known to arrange touch-sensitive contactstrips on the closing edges of automatically activated doors, whichstrips deactivated the door drive or reversed it to the openingdirection as soon as the respective touch-sensitive contact strip was incontact with an obstructing object or a person located in the dooropening.

Another known solution for protecting obstructing objects or personsbefore a closing, automatically activated door strikes them has been toextend a number of photoelectric barriers across the opening plane ofthe door or to provide the opening plane of the door with what isreferred to as a light curtain by means of a scanning light beam, asignal for deactivating or reversing the drive for the automaticallyactivated door being generated when said curtain is infringed at anypoint of the part of the opening plane which has not yet been taken upby the closing door. A very advantageous system of this type isdescribed, for example, in U.S. Pat. No. 6,218,940.

Automatically activated doors for very large door openings, for exampleof aircraft hangars, fire service equipment halls, assembly halls andthe like move at comparatively high speed both in the opening directionand in the closing direction, for which reason it may be found that eventhough an obstructing object which is to be moved to the door openingand has a part, for example the tips of forklift truck prongs, which isnear to the floor and extends to the opening plane, infringes the lightand brings about the triggering of a detector signal which triggers thedeactivation or reversal of the door drive, the deactivation or reversalof the door movement does not take place promptly enough for subsequent,upwardly projecting parts of the obstructing object, which is to bemoved onto the opening plane, to be sensed by the closing door and arethus damaged, and in particular also damage the door seriously.

Attempts have been made to counter these problems by installing inaddition to a security system which provides a light curtain whichextends across the opening plane of the door opening, for example bymeans of a detector beam or a plurality of detector beams, a furthersafety system which contains a movement sensor which is installedapproximately in the center of the door opening and which directsdetector radiation fields onto an approach area in front of the openingplane and whose infringement by an obstructing object which is movingtoward the opening plane of the respective door, or by a person who ismoving in a corresponding way, causes the automatic door drive to becontrolled in the door opening direction. The radiation fields of suchmovement sensors are fixed in this context.

In these known systems, the proximity sensor which is to be provided inaddition to the light curtain which monitors the door opening plane andwhich monitors approach areas on the inner side of the door or outerside of the door entails additional expenditure on equipment. It hasalso become apparent that the detector radiation fields of knownproximity sensors monitor the respective approach area only in adiscontinuous fashion in such a way that, for example, a child can passthrough between the monitoring radiation beams and thus reach theopening plane of the closing door without “advance detection”. Finally,movement sensors which are mounted above the opening of the door havethe disadvantage that, at a short distance in front of the openingplane, detector beams of the proximity sensor are directed very steeplydownward onto the approach area to be monitored and therefore ahorizontal speed of an obstructing object which is to be sensed or of aperson which is to be sensed only has a very small speed component inthe direction of the detector beam, such that movement sensors whichoperate according to the Doppler principle often have an inadequatesensitivity for the region of the approach area which is located near tothe opening plane.

It is to be noted that it is generally known to scan vertical monitoredregions, for example the facades of houses or else horizontal monitoredregions, for example areas of land, using scanning beams of a laserradar scanning detector and in this way to generate a monitoring signalwhen the respective monitored region is infringed, said signal being fedto a corresponding evaluation means. Furthermore it is known to generatea light curtain by means of a laser radar scanning detector within adoor opening which is located in a vertical plane, a monitoring signalwhich is used to control the door being triggered by means of thedetector when said light curtain is infringed by an obstacle.

BRIEF SUMMARY OF THE INVENTION

The invention is intended to achieve the object of configuring a devicefor automatically activating a door, in particular a lifting door, whichhas an essentially vertical opening plane, an inner side and an outerside, and approach areas which are near to the floor and arerespectively located on the inner side and on the outer side, in such away that a high degree of safety is achieved both against damage toobstructing objects or injury to persons impacting against the closingdoor as well as against damage to the closing door by obstructingobjects without a plurality of different monitor systems having to beprovided.

The invention is also intended to provide a device for automaticallyactivating a door which is very largely capable of replacing the knownsignal generating devices or control signal generators for opening thedoor or for monitoring the safety of the closing movement of the door,these being, for example, induction loops which are let into theapproach areas, movement sensors of all types, mats which react topressure, photoelectric barriers, scanning strips, pull switches and thelike.

This object is achieved according to the invention by means of anautomatically activatable door, in particular a lifting door, which hasan essentially vertical opening plane, lateral delimitations, an innerside and an outer side and approach areas which are level with the floorand are respectively located on the inner side and on the outer side,and an activating device, which comprises the following: a door drivewhich is coupled to the door; a monitor system, containing a detectorwhich operates according to the reflection principle and has the purposeof monitoring a region assigned to one of the approach areas, by meansof a detector beam for obstructing objects which possibly block aclosing movement, the monitor system generating a monitor signal when anobstructing object which is located in the respective approach area issensed; and a control device which is connected to the door drive, has amonitoring signal applied to it and has the purpose of deactivatingand/or changing the direction of the door drive which is in the doorclosing mode, when the monitoring signal occurs; characterized in thatthe detector is embodied as a scanning detector which is mounted next tothe lateral delimitations of the door opening at a height which ismatched to the maximum height of objects which are supported on therespective approach area and are not to be sensed as obstructingobjects, and which scans, with its scanning beam, a horizontal fanlocated above the respective approach area as a monitored region andwhich is shallow in the vertical direction, determined by the thicknessof the scanning beam, and whose radial dimension, which is determined bythe maximum measuring range of the scanning detector, is selected inaccordance with the magnitude of the respective approach area.

Advantageous refinements and developments are the subject matter of thedependent claims, whose content is expressly incorporated hereby in thepresent description without repeating the wording at this point.

The invention is based on the idea that obstructing objects or personswhich are about to penetrate the part of the opening plane which is notyet covered by a closing door, and are thus at risk of being struck bythe closing edge of the door, being jammed in it or of damaging thedoor, are in all cases supported on the ground in one of the approachareas and therefore penetrate the aforesaid part of the opening plane ofthe closing door, and in all cases infringe the horizontal monitoredregion which is in the form of the horizontal fan emitted by thescanning detector and is superimposed on the respective approach area ata short vertical distance, in such a way that, given appropriatedimensioning of this horizontal fan, there is no longer any need for adevice according to the invention to have a curtain-like monitoredregion extending across the door opening. Therefore, a highly simplifieddesign of the entire device is obtained together with increasedprotection against injuries to persons or damage to objects or to theclosing door.

It is significant that a laser radar scanning detector which is used asa scanning detector according to one preferred embodiment and which isalso often referred to as a laser scanner and is generally known per segenerates a highly focused detector scanning beam in such a way that aprecisely defined scanning horizontal fan can be produced by thescanning detector, within which fan the distances from obstructingobjects or parts of obstructing objects can be respectively measured bymeans of the scanning beam, in such a way that polar coordinates, thatis to say beam angles and radial obstruction distance, can be collectedwith respect to individual points on obstructing objects in relation tothe transmitter location as the zero point. The data which is collectedin this way can be processed in a variety of ways by comparingcorresponding coordinate values from successive scanning cycles.Different evaluations and correspondingly different processing programscan be executed without a significant restructuring of the equipment forthe device which is proposed here being necessary as a result.

Examples of a specific evaluation of the polar coordinatevalues—acquired in successive scanning cycles—of obstructing objectpoints are the lateral movement exclusion function, i.e. the exclusionof such detector output signals from a door activation process fordeactivating the closing movement or deactivating and reversing the doorinto the opening movement which indicate that the detector has sensed anobject moving in parallel with the door closing plane; in addition theexclusion of detector output signals from a door control operation ifsuch detector output signals indicate static obstacles which are alwayslocated in the approach area, or indicate objects which have been leftin the approach area and remain motionless for a specific time.

BRIEF DESCRIPTION OF THE DRAWINGS

A number of embodiments will be described in more detail below withreference to the drawing, in which:

FIG. 1 is a schematic, perspective view of a part of a building with adoor opening which can be closed by an automatically activated rollingdoor, and a monitor system in a device of the type specified here,according to a first embodiment;

FIG. 2 shows a plan view of a part of a building which is partiallyshown in a horizontal section and has a door opening and a device of thetype specified here, according to a second embodiment;

FIG. 3 shows a similar representation to FIG. 2 in a plan view with adevice of the type specified here, according to a third embodiment;

FIG. 4 shows a perspective view, seen from above, of a part of abuilding with a door opening and a device of the type specified here,according to a fourth embodiment;

FIG. 5 shows a similar view to FIG. 4 explaining a fifth embodiment;

FIG. 6 shows a plan view of a part of a building with a door opening anda device according to a sixth embodiment; and

FIG. 7 shows a similar view to FIG. 6 explaining a number of geometricideas in order to clarify particular advantages of the system specifiedhere.

DETAILED DESCRIPTION OF THE INVENTION

The scanning detector which is mentioned in the following statement ispreferably a laser radar scanning detector. The direction of the finelyfocused scanning beam of the scanning detector can be determined by thedirectional beam of the transmission and reception device.

FIG. 1 indicates a part 1 of a building which projects from the plane 2of the floor and is penetrated by a door opening 3. At the lateraldelimitations 4 and 5 of the door opening 3 there are door guiding andsupporting structures, for example guide rails, in which a laminatedroller door 6 is guided, which can be wound onto a roller 7 in order toopen the door, or unwound from the roller 7 in order to close the door,with the result that the closing edge 8 of the roller door 6 ultimatelydrops as far as the plane 2 of the floor. The roller door 6 is movedautomatically by means of a door drive 9 which is coupled to a controldevice 10 to which control signals are fed (in a fashion which is notillustrated) from a manually activated switch in such a way that anoperator can bring about the opening or closing of the roller door 6.

Furthermore, the control device 10 is connected to a monitor system 11which contains a detector 12 which operates according to the reflectionprinciple. The present exemplary embodiment is a laser radar scanningdetector which is mounted near to the lateral delimitation 4 of the dooropening 3 on the side of the door facing the viewer. The laser radarscanning detector 12 generates, as monitored region, a horizontal fan 13in the form of a circular segment which extends, for example, through90°. The laser radar scanning detector 12 is mounted at such a heightabove the plane 2 of the floor, on the part 1 of the building next tothe door opening 3, that the horizontal fan 13 is somewhat higher thanthe maximum height of animate beings or objects which are not to besensed as obstructing objects. Examples of such objects are fragments ofearth from the twin tires of trucks, relatively small amounts of lostpackaging material, birds which have landed on the floor, and the like.The height above the plane 2 of the floor may be, for example, 5 cm to50 cm, it being necessary to provide lower values, preferably over theinside approach area, and higher values over the outside approach area.

The approach areas 14 and 15, respectively, which are indicated byhatching are located, for example, on the outer side facing the viewerand the inner side facing away from the viewer, of the monitored door,said approach areas 14 and 15 each covering a semicircular region infront of or behind the door opening on the plane 2 of the floor in theselected example, the diameter being larger than the width of the dooropening. The radius of the circular-segment-shaped horizontal fan 13,that is to say of the monitored region of the laser radar scanningdetector 12, is selected in such a way that the horizontal fan 13 coversthe approach area 14 in all cases.

The radius of the horizontal fan 13, that is to say the maximummeasuring range of the scanning detector 12, can be determined, forexample, in that, after a radar pulse is emitted, the reception channelis kept open for the reception of any echo signals only during a limitedtime period which is determined by twice the propagation time of a radarpulse over the radius of the fan.

In the embodiment according to FIG. 1, a range or maximum measuringrange which is constant over the region which is scanned by the scanningbeam is provided such that the radius of the horizontal fan 13 is equalapproximately to the width of the door opening 3 plus twice the lateraloffset of the laser radar scanning detector 12 with respect to thelateral door delimitation 4, as is apparent essentially from FIG. 1.

Since the laser radar scanning detector 12 is mounted on the side of thepart 1 of the building, the horizontal fan 13 is shaded, with respect tothe door opening 3, by the wall of the part 1 of the building which isadjacent to the scanning detector 12, in such a way that the scanningdetector is capable of generating only a horizontal fan 13 which ispositioned over the outer approach area 14.

However, if, according to FIG. 2, the scanning detector 12 is mounteddirectly on an edge of the inner surface of the door opening 3 or on aninwardly pointing edge of the door guiding and supporting structures 16,the shadowing of the horizontal fan 13 by the parts of the building ordoor guiding and supporting structure parts which are adjacent to thescanning detector 12 is significantly less so that the horizontal fan 13can then have, for example, an angular extent of 220° and not only theoutside approach area 14 but also the inside approach area 15 of thedoor, and also the floor region directly in the door opening 3 arecovered in such a way that a continuous monitored region over bothapproach areas is obtained, at least during the period of time in whichthe roller door 6 is located with its lower edge or with its closingedge 8 above the level at which the scanning detector 12 is mounted.

If it is desired to use scanning fans of a scanning detector arrangementboth on the inner side and on the outer side of the gate to providecoverage of approach areas by means of monitored regions which are inthe shape of horizontal fans and which also extend to the side of thedoor opening 3 as far as the wall 1 of the building, as is shown for theapproach areas 14 and 15 in FIG. 1, two scanning detectors 12 and 12′can be provided according to the embodiment in FIG. 3, one of whichscanning detectors is mounted, for example, near to the right-handlateral delimitation 5 of the door opening 3, facing the outside of thedoor, and scans the horizontal fan 13 as a monitored region, while theother scanning detector 12′ is mounted near to the lateral delimitation4 of the door opening 3 on the inner side, and generates the horizontalfan 13′. Both horizontal fans 13 and 13′ are also retained when theroller door is completely closed, while in the embodiment according toFIG. 2 the part of the horizontal fan 3 which is in the shadow of theroller door and which is superimposed on one of the approach areas, isin the shadow when the roller door is closed. The outputs of thescanning detectors 12 and 12′ can be connected by means of an OR logicoperation and fed to the control device 10 (see FIG. 1).

FIGS. 2 and 3 show situations in which the outside approach area 14 andthe inside approach area 15 are at risk of being entered by obstructingobjects which are moving toward the door opening 3. An obstructingobject 18 which is located on the outer side, near to the approach area14, is, for example, in the form of a truck with a low driver's cab 19and a rear superstructure 20 which projects to a great height. Theobstructing object which approaches from the inner side of the dooropening 3 is, for example, in the form of a forklift truck 21 withlifting prongs 22 which protrude at a low level, a loaded pallet 23which is supported thereon, and the chassis with the driver's cab 24arranged thereon. It is apparent that, irrespective of the heightprofile of the obstructing object which approaches the door opening 3,said object must be supported in all cases on the floor in the approacharea 14 or in the approach area 15 on the way to the door opening 3, andfor this reason in all cases the supporting means, for example wheels,tires and the like, are detected promptly by the monitored region in theform of the horizontal fan 13 or the horizontal fans 13 and 13′, and thedoor drive 9 is deactivated or reversed in such a way that there is noneed for the monitoring light curtain, extending to a specific height,in the opening plane of the door opening 3.

FIG. 4 shows the possibility of using a single scanning detector 12,which is arranged near to a lateral delimitation, for example near tothe lateral delimitation 4, of the door opening 3, to generate ahorizontal fan 13 as a monitored region which both superimposes anapproach area on the outer side and an approach area on the inner sideof the door opening. For this purpose, a chamber, in which the scanningdetector 12 is installed, is built into the part 1 of the building whichcontains the door opening 3, near to the lateral delimitation 4 of thedoor opening. From the chamber, a passage extends to the lateraldelimitation 4 of the door opening 3, this passage also extendingthrough door guiding and supporting structures on the respective lateraldelimitation of the door opening 3 in such a way that these door guidingand supporting structures are interrupted over a short vertical distanceat the height where the scanning beam exits, so that the scanning beamcan pass through freely and can scan through the horizontal fan whichextends, for example, over 150°.

Another possible way of using a single scanning detector 12 to generatemonitored regions which are superimposed on the inside approach area andthe outside approach area is shown in FIG. 5. Here too, a chamber foraccommodating the scanning detector 12 is provided in the part 1 of thebuilding containing the door opening 3, near to the lateral delimitation4 of the door opening. However, said scanning detector 12 does nottransmit its scanning beam directly in the direction of the door opening3 but rather onto a distributor mirror 25 which is also located within achamber of the part 1 of the building and which transmits the scanningbeam to deflection mirrors 26 and 27 which are mounted on the outer sideand on the inner side of the part of the building. Horizontal ductswhich are provided for the beam path therefore extend from thedistributor mirror 25 through the wall thickness of the part 1 of thehousing and to the deflection mirrors 26 and 27, from which themonitored regions then proceed in the form of horizontal fans 13 and13′, respectively.

Embodiments according to FIGS. 4 and 5 have the advantage thathorizontal fans—superimposed on the outside approach area and the insideapproach area—of the scanning beams of the scanning detector 12 areretained even if the roller door has been lowered to below the level ofthe scanning detector 12. The following is to be noted with respect tothe evaluation of the output signals of the scanning detector 12 in asignal processing device which is associated with the monitor system 11:

If, according to the preferred embodiment in which the scanning detector12 is a laser radar scanning detector, a transmission pulse is emittedat a specific time, the time during which the reception channel for thereception of echo signals is kept open after the emission determines theradial dimensioning of the horizontal fan 13 and 13′, respectively,which is emitted by the scanning detector 12. In the embodimentsaccording to FIG. 1 to 5, the reception channel is kept open, forexample, for a constant time period after the emission of thetransmission pulse, for which reason the horizontal fans 13 and 13′,respectively, are each essentially in the form of a circular segment.

However, according to FIG. 6, it is also possible to select the timeperiod for which the reception channel is kept open after the emissionof the transmission pulse as a function of the angle through which thescanning beam is scanned in the horizontal plane, with the result that ahorizontal fan 13 is obtained which, despite the laterally offsetarrangement of the scanning detector 12, superimposes an approximatelysemicircular approach area 14 onto the outer side of the door opening 3.

It goes without saying that wherever the scanning beam of the scanningdetector 12 which scans within the horizontal fan 13 and 13′,respectively, strikes the part 1 of the building, for example thelateral delimitation 5 of the door opening 3 which lies opposite thelocation where the scanning detector 12 is mounted (for exampleembodiments according to FIGS. 2, 4 and 6), the scanning detector 12would signal an obstructing object which infringes its monitored regionin the form of the horizontal fan, in such a way that the monitor systemgenerates a monitoring signal and triggers the deactivation or reversalof the door drive 9. In order to prevent this, signal processing iscarried out on the output signals of the scanning detector, whichprocessing provides a fixed target suppression function, as is knownfrom radar technology. According to said function, monitor system outputsignals are generated only if a comparison between a current detectoroutput signal and a stored detector output signal from scanningoperations with analogous phases from preceding scanning cycles showsthat the scanning beam has been reflected by an object which was at adifferent radial distance from the scanning detector, in particular wasat a larger radial distance from the scanning detector during apreceding scanning cycle than was the case during the current scanningoperation. The signal processing device of the monitor system thereforecontains a deletion stage with storage means for storing echo signalscorresponding to their origin given a predetermined position of thescanning beam, and comparison devices for carrying out punctualcomparisons of current scanning signals, received from appropriatedirections, for the purpose of fixed character suppression. This makesit possible for objects which are always present, for example trees,boundary posts or the like, also to be arranged or installed in theapproach areas 14 and 15 without this disrupting the function of thedevice of the type specified here.

In a signal processing device which is acted on by the distance detector12, it is also possible to carry out a comparison of detector outputsignals from scanning directions of the scanning beam which are adjacentin terms of angle from the same scanning cycle or else from successivescanning cycles, with the result that signals are acquired in accordancewith an item of information about the direction of movement of anobstructing object. These comparison results which contain movementinformation and information about the direction of movement can belinked to the monitoring signals using logic operations, in such a waythat the door drive 9 is switched off or reversed whenever obstructingobjects which move in the approach areas 14 and 15 have a relativelylarge movement component in the direction of the door opening 3. Thesignal processing device can therefore execute specific signalprocessing programs which permit an obstructing object to be tracked,said programs being executed in such a way that whenever obstructingobjects move horizontally in parallel with the opening plane of the dooropening 3, no monitoring signals are generated, whereas monitoringsignals are derived from the detector signals if a movement componenttoward the door opening 3 is detected.

While the scanning detector, in particular therefore the laser radarscanning detector respectively supplies sets of obstacle pointcoordinates in the monitored region from one scanning cycle to the next,the coordinate information or the coordinate data is processed in thesignal processing device preferably taking specific defined safety zonesin the monitored region as a basis, it being possible to divide saidmonitored region into two zones, for example an absolute safety zone,which extends horizontally over the entire width of the door, andperpendicularly thereto, over a certain distance from the door closingplane, as well as a relative safety zone which is located at arelatively large distance from the absolute safety zone and at arelatively large distance from the door closing plane. In the absolutesafety zone, no objects at all are tolerated. Changes cause the door toopen. The door does not close again until the original state isrestored. In the relative safety zone, criteria such as speed ofapproach and the size of the movement component in the direction of thedoor opening are taken into account and different control decisions arerespectively taken.

The signal processing device also makes it possible to calculate thefollowing information about the movement of an obstructing object byreference to the obstructing object coordinate information which iscollected by the scanning detector in successive scanning cycles:

-   -   Entry point of the obstructing obstacle into the monitored        region    -   Direction of entry horizontally in relation to the door closing        plane    -   Entry speed and speed component in the direction perpendicular        to the door closing plane.

This information can be taken into account in the acquisition of themonitoring signal or in order to form a specific control signal or toset a specific reaction speed of the control device.

If the activated door is a sliding rolling door with vertical doorclosing edge which moves horizontally in the opening direction, inparallel with itself, given the same design and the same configurationof the scanning detector the previously mentioned calculation of theentry point of an obstructing obstacle into the monitored region can beused to form the control signals which cause the door to open with adifferent speed depending on whether an object approaches the dooropening near to the door delimitation which is located in the closingdirection or near to the door delimitation which is located in theopening direction.

Finally, a number of geometric considerations will be taken into accountwith reference to FIG. 7 in order to clarify particular advantages ofthe system specified here, but, as will be readily seen by a personskilled in the art, the invention is not restricted to the particularmathematical treatment of the information collected by the laserscanning detector but instead other processing possibilities of thepolar coordinate information of the output of the scanning detector arealso possible.

In FIG. 7, a part of a building is in turn designated by 1, a dooropening 3, which has a width w, being located in the part of thebuilding. An approach area which is on the inside of the door or on theoutside of the door is indicated by a dot-dashed line and designated by14 and 15, respectively. The laser radar scanning detector 12 is mountedon one side on a door opening delimitation in the previously mentionedspecific height above the approach area which is level with the floor,and transmits horizontal scanning beams in the horizontal direction witha time-dependent scanning angle α₁, α₂ . . . and β₁, β₂ . . . ,respectively.

In FIG. 7 it is assumed that the laser radar scanning detector 12carries out time-dependent scanning in the clockwise direction in afirst operating cycle (orientation angle of the scanning beam α₀, α₁, α₂. . . ) and in the directly following operation carries outtime-dependent scanning in the counter-clockwise direction (scanningangle β₀, β₁, β₂ . . . ). Such scanning can be generated by means of anoscillating mirror which is provided in the beam path of the scanningbeam.

If an obstructing object 18 moves in a direction parallel to thevertical plane of the door opening 3 into the approach area 14, 15, asis indicated by the arrow 30 which is indicated by means of adiscontinuous line, the first scanning beam of the laser radar scanningdetector 12 firstly strikes the obstructing object 18 at the scanningangle α₀, with the result that the laser radar scanning detector 12signals a distance a of the obstructing object from the vertical planeof the door opening 3.

All the following distance measuring values when the scanning angleassumes the values α₁, α₂ . . . in accordance with the angular speed ofthe scanning are inversely proportional to the cosine of the scanningangle α.

If, on the other hand, an obstructing object 21 enters the approach area14, 15 from the opposite side along a path which is indicated by thediscontinuous arrow line 31 and is parallel to the vertical plane of thedoor opening 3, it being assumed that the obstructing object 21 is notsensed by the laser radar scanning detector 12 until it crosses over thealignment line—oriented in the horizontal direction over the approacharea 14, 15 perpendicularly to the vertical plane of the door opening3—over the lateral door delimitation which lies on the right withrespect to the position in FIG. 7, the laser radar scanning detector 12signals a radial distance of the obstructing object 21 from the laserradar scanning detector 12 of r=w/cos β when this alignment line iscrossed.

If the arrangement is made such that obstructing objects 18 whichapproach from the left with respect to the illustration in FIG. 7 are tobe sensed during scanning in the clockwise direction and obstructingobjects 21 which approach from the right with respect to theillustration in FIG. 7 are to be sensed during scanning in thecounter-clockwise direction, the geometric relationships which are givenin the following table are obtained.

Scanning in the counter-clockwise Scanning in the clockwise directiondirection r cos α = a r cos β = w $r_{1} = \frac{a}{\cos\;\alpha_{1}}$$r_{1} = \frac{w}{\cos\;\beta_{1}}$ $r_{2} = \frac{a}{\cos\;\alpha_{2}}$$r_{2} = \frac{w}{\cos\;\beta_{2}}$$\frac{r_{1}}{r_{2}} = \frac{{a/\cos}\;\alpha_{1}}{{a/\cos}\;\alpha_{2}}$$\frac{r_{1}}{r_{2}} = \frac{w/{\cos\beta}_{1}}{{w/\cos}\;\beta_{2}}$$\frac{r_{1}}{r_{2}} = \frac{\cos\;\alpha_{2}}{\cos\;\alpha_{1}}$$\frac{r_{1}}{r_{2}} = \frac{\cos\;\beta_{2}}{\cos\;\beta_{1}}$$\frac{r_{1}}{r_{2}} > \frac{\cos\;\alpha_{2}}{\cos\;\alpha_{1}}$$\frac{r_{1}}{r_{2}} > \frac{\cos\;\beta_{2}}{\cos\;\beta_{1}}$Triggering! Triggering!

Therefore, if the ratio of successive distance measurements of the laserradar distance detector 12 is higher than the reciprocal value of thecorresponding cosine values of the scanning angles during scanning inthe clockwise direction, this means that the distance measurement of ascanning orientation which follows in the scanning direction becomessmaller and the obstructing object 18 takes on a travel component in thedirection of the door opening, deviating from the path according to thearrow 30. In this case, it is necessary to trigger a monitoring signalwhich deactivates a closing door or reverses it into the openingdirection or, if appropriate, also causes a closed door to open.

Completely corresponding considerations apply to the scanning directionin the counterclockwise direction, with scanning angles β which becomelarger over time.

It is apparent that the speed with which the scanning beam passes overthe approach area 14, 15 is selected to be expediently higher by anorder of magnitude than an assumed maximum travel speed of theobstructing object 18 and 21, respectively, that is to say is, forexample, qualitatively over ten times larger. Since the previouslyoutlined simple trigonometric calculations can easily be carried out inthe time interval when the scanning beam moves between two measuringpositions, real-time processing in order to derive monitoring signalsmay be performed. However, in contrast to this, it may be expedient incertain cases to buffer the distance data r₁, r₂ . . . collected fromthe laser radar scanning detector 12 in an assignment to the orientationof the scanning beam according to the scanning angles α₁ α₂ . . . andβ₁, β₂ . . . , respectively, over one or more scanning periods in orderto acquire time for an evaluation of the coordinate data.

With respect to the case of scanning in the counter-clockwise directionaccording to FIG. 7 in order to sense the obstructing object 21 whichmoves from the right into the approach area 14, 15 with respect to theillustration in FIG. 7, it is to be noted that this obstructing objectmay also pivot into a radial direction with respect to the laser radarscanning detector 12 shortly after entry into the sensing region of therespective scanning beam, for which reason it is expedient also to carryout a comparison of the distance measurements of scanning beams of thesame orientation of successive scanning cycles—in addition to thecomparison of the measured values corresponding to adjacent scanningbeams—in such a way that a monitoring signal is triggered immediatelywhen the radial distance from the laser radar scanning detector 12becomes smaller from one scanning cycle to the next.

The considerations presented above show that the device specified herediscriminates between parallel movements relative to the door openingplane and movements in the direction of the door opening even if, in oneembodiment, it has a laser radar distance detector only at a lateraldoor opening delimitation, by only carrying out distance measurementswithout the use of proximity sensor systems, in which case the signalevaluation algorithms are extremely simple and require only a minimumcomputational effort.

Door control photoelectric barriers, manually activated door controlswitches, induction loops which are used to control the door and are letinto the floor of the approach areas at large expense and withconsiderable technical effort and have the problem of connection to anyobstructing objects and light curtains, are replaced by a simple,comparatively cost-effective device which is easy to install.

1. Automatically activatable door which has an essentially verticalopening plane, lateral delimitations, an inner side and an outer sideand inner and outer approach areas which are level with the floor andare respectively located on the inner side and on the outer side, and anactivating device, which comprises the following: a door drive which iscoupled to the door and has a door opening mode and a door closing mode;a monitor system that has the purpose of monitoring a region assigned toat least one of the approach areas, the monitoring system including atleast a first detector that generates a detector beam for obstructingobjects which possibly block a closing movement of the door, and detectsecho signals from obstructing objects, the monitor system generating amonitor signal when an obstructing object which is located in therespective approach area is sensed by the detector; and a control devicewhich is connected to the door drive, is operatively coupled to themonitoring system to receive a monitoring signal from the monitoringsystem, deactivate and/or change the direction of the door drive if inthe door closing mode when the monitoring signal occurs; wherein thedetector is embodied as a scanning detector which is mounted next to alateral delimitation of the door opening at a height which is matched tothe maximum height of objects which are supported on the respectiveapproach area and are not to be sensed as obstructing objects, and whichscans, with a scanning detecting beam, a horizontal fan located abovethe respective approach area as a monitored region and which is shallowin the vertical direction, determined by the thickness of the scanningbeam, and whose radial dimension, which is determined by the maximummeasuring range of the scanning detector, is selected in accordance withthe magnitude of the respective approach area.
 2. The door as claimed inclaim 1, wherein the monitor system contains a further, second scanningdetector which is mounted near to the respective other lateraldelimitation of the door opening and corresponds in height and in theformation of the horizontal fan which is scanned by a scanning beamthereof, to the first scanning detector, the first scanning detectorbeing positioned in such a way that a scanning region thereof liesessentially over the outside approach area, while the second scanningdetector is positioned in such a way that a scanning region thereof liesessentially over the inside approach area.
 3. The door as claimed inclaim 1, wherein the door guiding and supporting structures and/oradjacent parts of a building are formed at the location where thescanning detector is mounted, near to the respective lateraldelimitation of the door opening, so as to be in such way transparentand free of obstacles for the scanning beam and wherein the monitoredregion of the scanning detector is in the form of at least onehorizontal fan which is located both over the inside and over theoutside approach areas, in such a way that the scanning beam of thescanning detector senses obstructing objects both on the inside approacharea and on the outside approach area.
 4. The door as claimed in claim3, wherein door guiding and supporting structures at the location wherethe scanning detector is mounted are interrupted over a short verticaldistance in such a way that they permit free passage of the scanningbeam in such a way that the horizontal fan extends uninterruptedly fromthe outside to the inside over the respective approach areas.
 5. Thedoor as claimed in claim 1, wherein the maximum measuring range of thescanning detector, or of each scanning detector, is controlled as afunction of pivoting angle thereof in the horizontal plane of thehorizontal fan.
 6. The door as claimed in one of claim 1, wherein thescanning detector, or each scanning detector, is an active radarscanning detector.
 7. The door as claimed in claim 6, wherein thescanning detector, or each scanning detector, is a laser radar scanningdetector.
 8. The door as claimed in claim 6, wherein the scanningdetector, or each scanning detector, is coupled to a signal processingdevice in which a monitoring signal is formed from a compositesignal—which exceeds a threshold value—of detector output signalscorresponding to identically oriented scanning beams from a plurality ofscanning cycles.
 9. The door as claimed in claim 6, wherein the scanningdetector, or each scanning detector, is coupled to a signal processingdevice in which a monitoring signal is formed by forming differences orforming relationships between current detector output signals and storeddetector output signals from scanning processes with analogous phasesfrom previous scanning cycles.
 10. The door as claimed in claim 6,wherein the scanning detector, or each scanning detector, is coupled toa signal processing device in which detector output signals fromscanning directions of the scanning beam which are adjacent in terms ofangle from successive scanning cycles are compared in such a way thatsignals corresponding to information about the direction of movement ofthe obstructing object, in particular relating to components which aretransverse with respect to the radial direction of the horizontal fanare acquired and are linked to the monitoring signals in order to beapplied to the control device.
 11. A method for automatically activatinga door which has an essentially vertical opening plane, lateraldelimitations, an inner side and an outer side and inner and outerapproach areas which are level with the floor and are respectivelylocated on the inner side and on the outer side, and an activatingdevice, which comprises the following: coupling a door drive to thedoor, the door drive having a door opening mode and a door closing modedrive; providing a monitor system that has the purpose of monitoring aregion assigned to at least one of the approach areas, the monitoringsystem including at least a first detector that generates a detectorbeam for obstructing objects which possibly block a closing movement ofthe door, and detects echo signals from obstructed objects, the monitorsystem generating a monitor signal when an obstructing object which islocated in the respective approach area is sensed by the detector; andoperatively connecting a control device to the door drive and to themonitoring system to receive a monitoring signal from the monitoringsystem and deactivate and/or change the direction of the door drive ifin the door closing mode when the monitoring signal occurs; mounting thedetector next to a lateral delimitation of the door opening at a heightwhich is matched to the maximum height of objects which are supported onthe respective approach area and are not to be sensed as obstructingobjects, and generating a scanning detecting beam and scanning in ahorizontal fan located above the respective approach area as a monitoredregion, the scanning beam being shallow in the vertical direction,determined by the thickness of the scanning beam, and having a radialdimension, which is determined by the maximum measuring range of thescanning detector, selected in accordance with the magnitude of therespective approach area.
 12. The method of claim 11, furthercomprising: detecting an echo beam generated when the scanning beamencounters an obstructing object in the monitored region, generating amonitor signal, detecting the monitoring signal with the control device,and at least one of deactivating and/or changing the direction of thedoor drive when in the door closing mode.